In recent years, a wide range of designs is needed for decorations in fields of the exterior of AV appliances, mobile phones, or household electric appliances and the interior of vehicles due to various customer preferences, and designs considering exterior appearance and texture of surfaces of products are required in some cases. In regards to the requirements, a concavo-convex pattern may be transferred to a surface of a product to apply a certain texture, in order to apply hairline or pleat having a concavo-convex pattern to a surface of a product as the design, in accordance with customer preferences. A concavo-convex pattern may be formed on a surface of a product by bonding a concavo-convex pattern to a surface of a product using a transfer film at the time of in-molding of a product.
First, a configuration of a typical transfer film having a concavo-convex pattern used in in-molding will be described with reference to FIG. 6. FIG. 6 is a sectional view showing a layer configuration of the typical concavo-convex pattern-attached transfer film.
Transfer film 201 having a concavo-convex pattern is a continuous film. Transfer film 201 having a concavo-convex pattern is broadly configured with carrier layer 202 which is not transferred to a molded product and transfer layer 203 which is to be transferred to a surface of a molded product. Transfer film 201 having a concavo-convex pattern will be more specifically described. A reference numeral 204 denotes a base film formed of PET or an acrylic film which has a function of continuously supplying transfer film 201 having a concavo-convex pattern into a die. A reference numeral 205 denotes a peeling layer which peels base film 204 and transfer layer 203 to be transferred to a molded product from each other, and a concavo-convex pattern is applied to peeling layer 205 in advance, in order to transfer the concavo-convex pattern to the outermost surface of transfer layer 203. A reference numeral 206 denotes a protective layer or a hard coat layer which has a concavo-convex pattern for applying a certain texture to an outermost surface of a molded product and applies strength or rigidity to transfer layer 203 to prevent scratches or contaminations. A reference numeral 207 denotes an anchor layer or a primer layer for easily performing ink printing and improving adhesiveness between ink and protective layer 206 or the hard coat layer. A reference numeral 208 denotes a coloring layer for applying a color, a pattern, or a design onto transfer layer 203 with ink. A reference numeral 209 denotes an adhesive layer which has a function of bonding a molten resin to transfer layer 203. As described above, transfer film 201 having a concavo-convex pattern is configured with a plurality of layers.
A manufacturing process for transferring transfer film 201 having a concavo-convex pattern described above to a surface of a molded product in an in-molding process will be described with reference to FIGS. 7A to 7H. FIGS. 7A to 7H are views explaining each step of an in-molding process.
In FIG. 7A, first, transfer film 201 having a concavo-convex pattern is transported to a predetermined position between fixed die 1 and movable die 2 using foil feeder 3. At this time, transfer film 201 having a concavo-convex pattern is disposed so that a transfer layer side of transfer film 201 faces movable die 2. Transfer type film 201 having a concavo-convex pattern may be transported into a die, after being preheated using a heater (not shown), so that transfer film 201 is easily shaped in a die. Next, after transfer type film 201 having a concavo-convex pattern is transported to a predetermined position, as shown in FIG. 7B, suction holes 4 penetrated through a cavity surface of movable die 2 suck transfer type film 201 having a concavo-convex pattern, and transfer type film 201 having a concavo-convex pattern is shaped onto the cavity surface of movable die 2. At that time, the outer periphery of transfer type film 201 having a concavo-convex pattern is fixed by a film pressing mechanism (not shown) and transfer type film 201 is positioned. After that, as shown in FIG. 7C, movable die 2 is moved to clamp the fixed die. Then, as shown in FIG. 7D, molten resin 6 is injected towards an adhesive layer of the surface of transfer type film 201 having a concavo-convex pattern by gate 5 of fixed die 1, and the inner portion of the cavity in the die is filled with molten resin 6. Next, as shown in FIG. 7E, when the filling with molten resin 6 is completed, molten resin 6 is cooled to a predetermined temperature. Then, as shown in FIG. 7F, movable die 2 is moved to be released from the fixed die, carrier layer 202 of transfer type film 201 having a concavo-convex pattern is peeled off from in-mold molded product 7 and only transfer layer 203 is transferred, when extracting the in-mold molded product 7, and thus, a state in which transfer layer 203 having a concavo-convex pattern is transferred to an outermost surface of in-mold molded product 7 is obtained. After that, as shown in FIG. 7G, knock-out pins 8 on fixed die 1 side are pressed to extract molded product 7 from the inner portion of the die. Finally, as shown in FIG. 7H, suction performed by suction holes 4 of movable die 2 with respect to the carrier layer of transfer type film 201 having a concavo-convex pattern into the cavity of movable die 2 is stopped for the next molding. Transfer type film 201 having a concavo-convex pattern used in the next molding is transported to a predetermined position by foil feeder 3, and this operation is repeatedly performed to perform continuous molding (see PTL 1).